Platelet-activating factor (PAF) has been associated with various biological activities and pathways, thus making it an important mediator responsible for a variety of physiological processes including, but not limited to, activation and aggregation of platelets, smooth muscle contraction, pathogenesis of immune complex deposition, inflammation, immunomodulation, respiratory, cardiovascular and intravascular alterations. These physiological processes are associated with a large group of diseases, such as, for example, cardiovascular disorders, asthma, lung edema, endotoxin shock, adult respiratory distress syndrome and inflammatory diseases, autoimmunization and graft rejection.